On Sat, May 19, 2018 at 2:56 AM, MRAB <pyt...@mrabarnett.plus.com> wrote:
> On 2018-05-18 12:22, Ken Hilton wrote:
>>
>> Hi all,
>>
>> Yes, this is another idea for avoiding breaking existing code when
>> introducing new keywords. I'm not sure if this is too similar to Guido's
>> previous "allow keywords in certain places" idea, but here goes:
>>
>> Only treat keywords as having any special meaning when they are in places
>> with syntactical significance.
>> So, currently, let's say someone set the variable "and_" to some value.
>> The following lines are both SyntaxErrors:
>>
>> True and_ False
>> obj.and = value
>>
>> And the following are both correct:
>>
>> True and False
>> obj.and_ = value
>>
>> My idea is to only treat keywords as having special meaning when they're
>> in the right place. So the following would all be legal:
>>
>> >>> from operator import and
>> >>> var = and(True, False)
>> >>> var
>> False
>> >>> var = True and False
>> >>> var
>> False
>> >>> def except(exc, def):
>> ... try:
>> ... return def()
>> ... except exc as e:
>> ... return e
>> ...
>> >>> except(ZeroDivisionError, lambda: 1/0)
>> ZeroDivisionError('division by zero',)
>> >>> except(ZeroDivisionError, lambda: 0/1)
>> 0.0
>> >>> import asyncio as await #this is already currently legal, but
>> will not be in the __future__
>> >>> async def async(def):
>> ... return await await.get_event_loop().run_in_executor(None,
>> def)
>> ...
>> >>>
>>
>> And so on.
>>
>> What are your thoughts?
>>
> This would be legal, but what would happen?
>
> def yield(x):
> print('YIELD')
>
> def foo():
> yield('FOO')
>
> f = foo()
"yield" would have to be a keyword in any context where an expression
is valid. Which, in turn, makes it utterly useless as a function name,
or any other identifier.
ChrisA
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